Objective: The primary objective of this core is to produce and provide monoclonal antibodies (Mab's) specific for unique surface markers that characterize specific stages during stem-cell to beta-cell maturation. By combining forefront expertise in relevant promoter selection with different stem-cell sources to produce staged cells that are expandable we will apply state-of-the-art hybridoma technology/phage-display library large scale screening to produce and identify such antibodies. In addition, micro-array-analysis of such cells may allow identification of potential cell surface antigens for Mab or polyclonal antibody generation. Antibodies directed against unique surface markers will be mandatory future tools to monitor ex vivo stem-cell maturation towards the mature beta-cell. Such antibodies will allow not only selection of desired sub- populations (FACS/MACS)-but moreover facilitate screening assays for factors necessary to drive the maturation process in descrete steps. Such progress is mandatory for reaching the long term goal of being able to produce fully normal non-modified beta-cells from desired stem-cell sources. Additionally, Mab's or polyclonal antisera against stage-specific internal markers, including transcription factors will be produced to facilitate documentation of the success of the maturation process.